Tony Dokoupil considers them:
This much is obvious: the upsides of legalization have been wildly oversold, and the potential downsides blithely ignored. I’d like to correct that balance, not because I support prohibition but because I think legalization should succeed or fail on the merits, as much as they can be known.
The harms he foresees:
We know enough, however, for serious concern. The mantra of marijuana legalization is “Safer than Alcohol,” which—to be fair—is generally true. But safer than alcohol is not the same as “safe.” Every year about 375,000 people end up in the ER with marijuana-related “averse reactions,” more than any drug other than cocaine. Some of those cases are the result of multiple drug interactions, where marijuana gets the blame while cocaine does the damage. But for many tens of thousands of ER visits marijuana is the only drug mentioned. And there’s even data suggesting that, as the authors of “Marijuana Legalization” put it, “marijuana can kill.” Between 1999 and 2007, the Centers for Disease Control, somewhat curiously, attributed 26 deaths to cannabis use—half in the subcategory “dependence.”
But at least pot isn’t addictive, right? Wrong. More than 4 million people self-report behavior that meets the clinical criteria for marijuana dependency or abuse. The “capture rate,” as scholars call it, was once about 9 percent, according to one study, but for people who start before age 25—as almost everyone does today—it jumps to 15 percent, the same capture rate as alcohol and just a percentage point less than cocaine. Drug treatment programs for marijuana have fives times the number of enrollees as they did just two decades ago. Most are referred by the U.S. criminal justice system, but many are not—and enrollment has more than doubled in European and Australian programs as well.